Quality Control

Biological Activity

LEE011 is an orally available, small-molecule inhibitor of cyclin-dependent kinases (CDK) which targeting cyclin D1/CDK4 and cyclin D3/CDK6 cell cycle pathway, with potential antineoplastic activity. CDK4/6 inhibitor LEE011 specifically inhibits CDK4 and 6, thereby inhibiting retinoblastoma (Rb) protein phosphorylation. LEE011 caused cell-cycle arrest and cellular senescence that was attributed to dose-dependent decreases in phosphorylated RB and FOXM1, respectively. In addition, responsiveness of neuroblastoma xenografts to LEE011 translated to the in vivo setting in that there was a direct correlation of in vitro IC50 values with degree of subcutaneous xenograft growth delay. Treatment with LEE011 significantly reduced proliferation in 12 of 17 human neuroblastoma-derived cell lines by inducing cytostasis at nanomolar concentrations (mean IC50 = 307 ± 68 nmol/L in sensitive lines). LEE011 is currently in Phase I development by Novartis.

Protocol

Cell Experiment

Cell lines

MYCN amplified neuroblastoma cell lines

Preparation method

Pharmacologic growth inhibition LEE011 was provided by Novartis pharmaceuticals. A panel of neuroblastoma cell lines, selected based upon prior demonstration of substrate adherent growth, was plated in triplicate on the Xcelligence Real-Time Cell Electronic Sensing system (ACEA Biosciences) and treated 24 hours later with a four-log dose range of inhibitor or with a DMSO control. Cell indexes were monitored continuously for ~100 hours, and IC50 values were determined as follows: Growth curves were generated by plotting the cell index as a function of time and were normalized to the cell index at the time of treatment for a baseline cell index of 1. The area under the normalized growth curve from the time of treatment to 96 hours post-treatment was then calculated using a baseline area of 1 (the cell index at the time of treatment). Areas were normalized to the DMSO control, and the resulting data were analyzed using a non-linear log inhibitor vs. normalized response function (Graphpad). All experiments were repeated at least once.

Conversion of different model animals based on BSA (Value based on data from FDA Draft Guidelines)

Species

Mouse

Rat

Rabbit

Guinea pig

Hamster

Dog

Weight (kg)

0.02

0.15

1.8

0.4

0.08

10

Body Surface Area (m2)

0.007

0.025

0.15

0.05

0.02

0.5

Km factor

3

6

12

8

5

20

Animal A (mg/kg) = Animal B (mg/kg) multiplied by

Animal B Km

Animal A Km

For example, to modify the dose of resveratrol used for a mouse (22.4 mg/kg) to a dose based on the BSA for a rat, multiply 22.4 mg/kg by the Km factor for a mouse and then divide by the Km factor for a rat. This calculation results in a rat equivalent dose for resveratrol of 11.2 mg/kg.